The principal goals of the set of experiments proposed here is to take advantage of the unique opportunity which is offered by the duplicate Adh genes of D. mojavensis for identification, isolation and characterization of the genetic information which specifies cell specific gene function. We also hope to learn about the role of chromosomal events which occur during evolution and have as their consequence alternate regulatory patterns of gene expression. These studies will utilize the duplicate Adh loci of Drosophila mojavensis to examine the structure of genes which are differentially regulated during development. D. mojavensis and other Mulleri subgroup flies have two Adh genes. There are cell types in which one is expressed, other cells in which the other gene is expressed and a third class of cells in which both are expressed. In addition D. mojavensis has a more recent evolved pattern of expression of Adh-1. Only in this species and its sibling, is Adh-1 expressed in the ovary. The Adh genes form D. mojavensis will be cloned, isolated, and sequenced in order to identify regions of sequence that may be involved with tissue specific function of each gene. In addition we will compare Adh locus structure in several species which are of interest because of having an altered evolutionary history of Adh locus structure and/or regulation. These include species that may have lost a duplicate Adh gene and species that have duplicate Adh genes but their duplication may be the result of event independent of the event that occurred in the ancestors of D. mojavensis. We will compare the regulatory pattern of Adh expression in three species. D. mojavensis, D. arizonensis and D. navojoa to understand the adaptive significance of the Adh duplication and variant patterns of tissue specific gene expression. Finally we will begin experiments to introduce intact or modified Adh genes of D. mojavensis into D. melanogaster by P element mediated transformation.